The present invention relates to a tool connecting device for robot hands. More specifically, the present invention relates to a tool connecting device for robot hands that allows tools to be switched quickly and reliably without dropping of parts and the like.
An example of a generally known tool connecting device for robot hands that allows one out of a plurality of tools to be selectively attached to and detached from a hand section of a robot hand includes: an inner assembly (master plate) attached to the hand section of the robot hand; an outer assembly (tool plate) to which tools are attached; and a locking mechanism that locks together the inner assembly and the outer assembly.
U.S. Patent No. 4,696,524 describes a tool coupling device that allows quick connecting and disconnecting of the inner assembly and the outer assembly for tool connecting devices for robot hands described above. The lock mechanism for this tool coupling device for robot hands includes: a piston member; ball members serving as a plurality of engagement members; and a ball receiver serving as an engagement section.
The piston member described above is supported by the inner assembly and can slide between a locked position and an unlocked position. The ball members are held in retainer openings of a roughly cylindrical ball retainer connected to the inner assembly and extending along the outer perimeter of the output section of the piston member. The ball members are supported so that they can move in a direction perpendicular to the direction in which the piston member slides (hereinafter referred to simply as the perpendicular direction). Thus, in the retainer openings of the ball retainer, the radially inward side and the radially outward side are connected in the perpendicular direction, and the ball members can move in the perpendicular direction within the retainer opening.
The ball receiver is disposed on the outer assembly and is formed with a tapered surface that can come into contact with the ball members. When the piston member moves to the locked position, the ball receiver cooperates with the ball members to connect and support the inner assembly and the outer assembly.
A plurality of plate springs are disposed on the ball retainer along the outer perimeter surface of the ball retainer but not at the retainer openings. The ends of the adjacent plate springs serve to prevent ball members from dropping down and push the ball members toward the radially inward side of the ball retainer, especially when the connection between the inner assembly and the outer assembly is released.
Japanese laid-open patent publication number 4-63688 presents a tool connecting device for robot hands that also prevents ball members from dropping by using a plurality of plate springs disposed along the outer perimeter surface of a ball retainer. These plate springs prevent the ball members from dropping out from the ball retainer.
With these type of tool connecting device for robot hands, a plurality of plate springs must be disposed in order to push the ball members radially inward in the ball retainer and prevent them from dropping out. This requires a complex structure and a large number of parts, thus increasing production costs. Furthermore, since ball members are used as engagement members, a point contact is formed between the spherical surface of the ball member and the flat surface of the ball receiver. Because of the resulting small contact area, the contact surface pressure on the ball member becomes high. Thus, the durability of the lock mechanism is short.
The object of the present invention is to provide a robot hand tool connecting device attaining a long durability, low production costs, simplified structure, and a small number of parts and that also reliably prevents the engagement members from dropping out.
The present invention provides a tool connecting device for robot hands including: a master plate connected to a hand section of a robot hand; a tool plate connected to a tool; and locking means removably locking the master plate and the tool plate. Locking means includes: a piston member supported by the master plate and capable of sliding between a locked position and an unlocked position; a retainer fixed to the master plate and extending along the outer perimeter of an output section of the piston member; a plurality of roller members supported in a plurality of retainer openings of the retainer and capable of moving in a direction perpendicular to the direction in which the piston member slides; engagement sections disposed on the tool plate and engaging with the plurality of roller members. Each of said plurality of roller members is formed from a roller member, and projections are disposed at the center of the side surfaces of each roller member perpendicular to the axis thereof. Guide grooves are formed at the sides of the retainer openings of the retainer to guide the pairs of projections on the roller members and to prevent them from falling out.
In this tool connecting device for robot hands, when the master plate and the tool plate are to be connected, the piston member is made to slide to the locked position, and the roller members in the retainer openings are moved outward in a direction perpendicular to the direction in which the piston member slides. The roller members are fitted between the engagement section and the output section of the piston member, thus locking the master plate and the tool plate. The roller members are guided so that the pairs of projections thereof do not fall out from the guide grooves formed at the sides of the retainer openings.
When the master plate and the tool plate are to be unlocked, the piston member is made to slide to the unlocked position. The roller members in the retainer openings are then able to move inward in the direction perpendicular to the direction in which the piston member slides, thus unlocking the plates. Since the roller members are guided so that the pairs of projections thereof do not fall out from the guide grooves, the roller members can be reliably prevented from falling out, while the need for a plurality of plate springs that prevent the engagement members from falling out is eliminated. Thus, the number of parts can be reduced and the structure can be simplified. Since the engagement members are formed as roller members, line contacts are formed at least between the roughly cylindrical surfaces of these roller members and the engagement sections. Thus, compared to the conventional ball members, the contact area is larger and the contact surface pressure can be reduced. This improves the durability of the locking means and allows the durability of the tool connecting device for robot hands to be improved.
Preferably, the pair of projections of each roller member is formed integrally with the roller main body. This provides a simplified structure and reduces the number of parts, thus lowering production costs. Also, preferably, the pair of projections of each roller member is formed as the ends of a pin member mounted in an axial opening of the roller main body. This makes producing of the roller main body easier, and the mounting of the pin member in the roller main body can be performed easily.
In the tool connecting device for robot hands described above, it would be desirable to have an air cylinder including the piston member disposed on the master plate. The air cylinder drives the piston member between the locked position and the unlocked position. By driving the piston member between the locked position and the unlocked position, the air cylinder is able to lock and unlock the master plate and the tool plate reliably and simply.
Furthermore, it would be desirable to have a structure in which, when the piston member is at the locked position, the plurality of roller members is supported at a projected position projecting from the outer surface of the retainer and engaging with the engagement section, and, when the piston member is at the unlocked position, the plurality of roller members is able to move between the projected position and a recessed position inward from the outer surface of the retainer. With this structure, the master plate and the tool plate can be connected and disconnected reliably according to the positions of the piston member.
It would be desirable to have a tapered section formed on the engagement section that is tapered radially inward toward the master plate. When the piston member is in the locked position, the roller members in the projected position can engage with the tapered section of the engagement section, thus allowing the master plate and the tool plate to be reliably locked.
It would also be desirable to have a contact section disposed on the tool plate that is able to form a surface contact with a section of the outer perimeter surface of the roller member. When the roller member is in contact with the engagement section, a surface contact is formed with the contact section. This increases the contact area for the roller member and further reduces the contact surface pressure, thus significantly improving the life span of the locking means.
It would be desirable to have the plurality of roller members supported in a plurality of retainer openings formed at appropriate intervals along the perimeter of the retainer. By having the plurality of rollers engaged with the engagement sections, the master plate and the tool plate can be reliably locked.
It would also be desirable to have a plurality of engagement sections formed on the tool plate at positions corresponding to the plurality of roller members. This allows the plurality of engagement sections to be formed easily by cutting away tool plate members, thus allowing production costs to be reduced.
It would also be desirable to have the guide grooves formed as U-shaped grooves opening inward. This reliably prevents the roller members from dropping out from the retainer and allows the roller member to be reliably assembled into the retainer openings of the tool plate from the inside.
It would be desirable for a restricting section to be disposed on the piston member to restrict the roller members from moving inward from the recessed position when the piston member is in the unlocked position. When the piston member is in the unlocked position, the restricting section prevents the roller members from moving inward from the recessed position, and this reliably prevents the roller members from falling toward the inside of the retainer.
It would be desirable for the air cylinder to be a double-action air cylinder. This allows the piston member to be reliably moved between the unlocked position and the locked position. It would also be desirable for the piston member to be a single-action air cylinder. This allows the piston member to be reliably moved at least from either the unlocked position to the locked position or vice versa. In this case, it would be desirable to have the piston member kept in the locked position when the air cylinder is inactive using a spring member or the like. When the air cylinder is activated, the piston member can then be moved to the unlocked position.
Briefly stated, the present invention provides roller member connectors that facilitate quick change of tools used by robot hands. Each roller member includes a pair of projections on either side thereof. On the inner surface of each retainer opening, a pair of guide grooves are formed to guide the projections so that they are retained during operation.
According to an embodiment of the invention, there is provided a tool connecting device for robot hands comprising: a master plate connectable to a hand section of a robot hand; a tool plate connectable to a tool; a piston member movably supported by the master plate and slidable between a locked position and an unlocked position; a retainer fixed to the master plate; the retainer extending along an outer perimeter of an output section of the piston member; the retainer having a plurality of roller members; a plurality of retainer openings in said retainer; the roller members being supported in the plurality of retainer openings of the retainer and movable in a direction perpendicular to a direction in which the piston member slides; a plurality of engagement sections disposed on the tool plate; and the plurality of engagement sections engaging with the plurality of roller members.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.